Embodiments of the inventive concepts relate to a micro ballpoint pen and a printing apparatus, and in particular, a micro ballpoint pen configured to perform a printing operation in a direct contact manner, and a printing apparatus including the same.
Electronic devices may be fabricated using fine and elaborated printing methods, e.g., inkjet printing, screen printing, offset printing, flexography, and gravure. For example, these printing methods may be applied to various technical fields, such as a flat-panel display device (e.g., a liquid crystal display (LCD), an organic light emitting device (OLED), an organic thin film transistor (OTFT)), a flexible display device (e.g., E-paper), a printed electronics (e.g., metal wires), or bio-electronics.
In the inkjet printing method, tiny ink droplets may be ejected on a desired position of a target printing object to form a printed image. However, there are technical difficulties in controlling exactly a falling position of the ink droplet, changing a printing thickness range, preventing ink from being blurred, and printing a continuous line. By contrast, all of screen printing, offset printing, flexography, and gravure may need an engraving resulting in an increase in ink consumption and a limitation in printing resolution.
There is a near-field electro-spinning method, which is one of line printing methods, not a point or plane printing method. However, for the near-field electro-spinning method, a line is printed using a high electric field, it is hard to print a dashed line, a bulge may occur at an end of line, and there is a limitation in using various kinds of inks. In addition, since the method is sensitive to a distortion of electric field, it is hard to prevent an interference issue, especially in the case of using a multi-nozzle.
Furthermore, there is a dip-pen or nano fountain-pen method, which is developed from an atomic force microscope (AFM) measuring a fine structure in an atomic level, but this method suffers from a very expensive apparatus cost and a small printing area.
So far, there has been a technical difficulty in applying a ballpoint pen for a high resolution printing apparatus. This is because it is hard to control exactly a ball gap, which is formed between a ball and a pen tip, and through which ink is outflowed by a rolling ball. In other words, it is hard to control an ejecting amount of ink exactly. To realize a high resolution printing, it is necessary to be able to control finely the ball gap, a pressure applied to a target object by a ball, a frictional force at an interface, a revolution number of a ball.